Thermally stable viscous materials containing bromofluorohalogenated alkane oils



July 18, 1961 w. s. BARNHART 2 992 9 THERMALLY STABLE VISCOUS MATERIALS CONTAINING 89 BROMOFLUQROHALOGENATED ALKANE OILS Flled March 20, 1957 TEMPERATURE F.

INVENTORS WILLIAM S. BARNHART CHARLES W. WEBER BY JOSEPH L- ZOLLINGER ,8. 11'. FM 6'. W

ATTORNEYS United States atent (3 f6 THERMALLY STABLE VISCOUS MATERIALS CON- TAINING BROMOFLUOROI-IALOGENATED AL- KANE OILS William S. Barnhart, Cranford, Joseph L. Zollinger, Bloomfield, and Charles W. Weber, Jersey City, N.J., asslgnors, by mesne assignments, to Minnesota Mining and Manufacturing Company, St. Paul, Minn., a corporation of Delaware Filed Mar. 20, 1957, Ser. No. 647,335 11 Claims. (Cl. 252-58) This invention relates to a thermally stable viscous material and to the preparation thereof. In one aspect this invention relates to a flotation fluid for reducing frictional losses in instruments and machines. Another aspect of this invention relates to a damping fluid for reducing impact and vibration damage which oifers viscous, nonelastic restraint to moving parts within a gyro. Another aspect of this invention relates to a bromofiuorohalogenated viscous material having a low pour point and high shear stability. Another aspect of this invention relates to a br'omofluorohalogenated oil having a viscosity which is substantially stable over a wide temperature range and a low clear point. Still another aspect of this invention relates to a bromofluorohalogenated material as a damping and flotation fluid for gyro mechanisms.

Gyro mechanisms which are used for missile guidance systems, aircraft navigation instruments, fire control systems and navigation instruments on ships have now achieved wide recognition. A present day need for improving operating characteristics of gyros is a highly viscous, high density material which has a low pour point and which is stable at moderate temperatures, that is, at temperatures of about 200 F. A gyro in a guided missile, for example, in responding to change in speed, direction and attitude may provide the only stable reference with respect to the earth by which the missile can be navigated. Precision required in the control of high speed, long range missile and aircraft has placed new demands upon gyros. To meet these demands a relatively new floated gyro has been designed which requires a suitable fluid to float the gyro. Various fluids and waxes have been employed for this purpose but these have not been able to meet the requirements demanded for a material of this type. Typical specifications for a gyro fluid which is used to float the gyro in an integrating machine are presented in Table I.

1 Greater then.

In other cases, where the gym is fixed to the casing by a resilient member and where the fluid is not required to float the gyro, the viscosity requirements are much lower than those recorded above in Table I. For example, a viscosity of between about 100 and about 1,000 centipoise at 100 F., may be required. Another specification requires a viscosity within this range and a density of about 1.8 at 100 F. Additional requirements of some of these gyro fluids is that they remain liquid at low temperatures and have pour points well below room temperature. With some gyros now in design, the density may be as low as 1.78 or lower. Thus, it is observed that requirements for.

gyro fluids may vary considerably depending upon the particular mechanism in which the fluid is to be employed.

Other instruments such as bi-metallic dial type thermometers, and chemical seal pulsation damp-eners have also indicated a need for a highly viscous materialwhich meets many of the specifications mentioned above,

It is, therefore, an object of the present invention to provide a thermally stable viscous material having a low pour point and to provide a method for the preparation thereof.

Another object of this invention is to provide a thermally stable viscous bromofiuorohalogenated material which remains clear at room temperature. 1

Another object of this invention is to provide a bromofluorohalogenated material which is relatively non-volatile at temperatures up to 200 F.

Another object of this invention is to provide a perbromofluorohalogenated material for use as a damping and flotation fluid in a gyroscope.

Still another object of this invention is to provide a commercially feasible method for the preparation of a thermally stable viscous material for use as a damping and flotation fluid.

Other objects and advantages of the present invention will become apparent to those skilled in the art from the accompanying description and disclosure.

According to this invention a normally solid polymer, such as, for example, chlorotrifluoroethylene and vinylidene fluoride copolymer having a specific gravity (Jolly Balance) at F. of about 2.02 and a dilute solution viscosity (DSV) of between about 0.5 and about 2.0 at 266 F., is admixed with, and dissolved in, a major portion of a bromofluorohalogenated oil containing between 4 and 12 carbon atoms per molecule.

The dilute solution viscosity (DSV) of the normally solid polymer is determined by dissolving a sample of the polymer in 2,5-dichlorobenzotrifluoride to a concentration of 0.75 weight percent solvent. The sample is mixed with the dichlorobenzotrifluoride in a flask which is placed in a bath at 300 F. and stirred for 3 to 4 hours or until the sample is completely dissolved. The resulting solution is removed from the flask and poured into a modified Ubbelohde viscosimeter equipped with a sinter disk through which the solution is filtered. The viscosimeter is maintained at 266 F. by means of a thermostatically controlled bath. The liquid is drawn up through a graduated, calibrated capillary of the viscosity tube and the time it requires for the liquid to descend from one point in the graduated capillary to another is recorded in seconds. This value is multiplied bythe factor of the tube to obtain a value in centistokes. This method of measuring viscosity has been applied to solid polymers having dilute solution viscosities between about 0.5 and about 3 or higher when the polymer is soluble in the solvent at the given temperature.

The bromofluorohalogenated oils of the present invention containing between 4 and 12 carbon atoms per molecule are aliphatic bromofluorinated oils and aliphatic bromofluorochlorinated oils wherein each bromine atom is bonded to acarbon atom and wherein the remaining substituents on the bromine substituted carbon atoms are normally gaseous halogen atoms (chlorine and fluorine atoms). The preferred aliphatic bromofluorohalogenated oils of the present invention are perhalogenated oils wherein the ratio of bromine to carbon is between 121 and 1:6 and most preferred of this group are the aliphatic perbromofluorohalogenated oils which correspond to the followinggeneral formulae:

. wherein m is an integer between 0 and 3 and Y is a halo wherein n is an integer between and 4.

The perbromofiuorohalogenated oils corresponding to the above formulae are prepared by brominating with molecular bromine the corresponding olefins at a temperature of from about 20 C. to about 100 C. or with actinic light such as ultra-violet radiation and removing the corresponding brominated product by distillation or by any other convenient means, such as, for example, by the removal of excess bromine with chlorotrifluoroethylene, with aqueous sodium bisulfite or with ethylene followed by fractionation of the mixture. The olefins which are subjected to bromination in the process of this invention to yield compounds which correspond to Formula 2 of the most preferred group of the perbromofiuorohalogenated' oils, are the monoolefinic products namely CF =CF(CF -CFCl) CF -CFCl wherein -n is an integer from 0 to 4; and are obtained by the 'monoand diolefins obtained from the thermal cracking of a chlorotrifluoroethylene polymer, for example, the monoolefin CF OF-(CF -CFCI) -OF CFCI wherein m is an integer between 0 and 4 and the diolefin CF =OF(OF CFCl) CF -CF=CF wherein n is an integer from 0 to 3 are both obtained 'by the process described in US. application Serial No.

525,783, filed August 1, 1955, in the names of E. Fischer and H. Frey, now US. 2,854,490. These olefins can be separated and their bromine addition products used individually as a perbromofluorohalogenated oil or the pyrolysis product mixture can be brominated in toto to produce a mixture of perbromofluorohalogenated oils which can be employed as the perbromofluorohalogenated oil of the present solutions.

The monoolefin,

wherein n is an integer between 0 and 3 is prepared by the decarboxylation of a perchlorofluoromonocarboxylic acid, namely wherein n is an integer between 2 and 5 and is described in US. application Serial No. 517,926, filed June 24, 1955, in the names of W. S. Barnhart and R. H. Wade. The bromination of this monoolefin produces a perbromofluorochlorinated alkane corresponding to Formula 1 wherein the Y substituents are chlorine atoms; however, this monoolefin can be dechlorinated with zinc to produce the diolefin,

OF =C*F( CF OFCl) CF CF=CF wherein n is an integer between 0 and 3. This diolefin is also one of the products obtained from the pyrolysis of chlorotrifluoroethylene polymer and the bromination of this diolefin produces a perbromofluorochlorinated alkane corresponding to Formula 1 wherein the Y substituents are bromine atoms.

Specific examples of members of this most preferred group of perbromofluorohalogenated oils are 1,2,6,7-

tetrabromo-4-chloroundecafiuoroheptane, 1,2-di-bromo-4,

4 6,8,9-tetrachlorotetradecafluorononane, 1,2-dibromo-4,5- dichlorooctafluoropentane, 1,2,4,S-tetrabromooctafluoropentane, 1,2-dibromo-4,6,7-trichloroundecafluoroheptane, 1,2 dibromo 4,6,8,10,11 pentachloroheptadecafluorohendecane, 1,2 dibromo 4,4 dichlorohexafluorobutane, 1,2 dibromo 4,6,6 trichlorononafluorohexane, 1,2 dibromo 4,6,8,10,10 pentachloropentadecafluorodecane, 1,2 dibromo 4,6,8,10,12,12 hexachlorooctadecafluorododecane, 1,2 dibromo 4,6,8,8 tetrachlorododecafluorooctane, 1,2,10,11-tetrabromo-4,6,8-trichloroheptadecafluorohendecane, 1,2,8,9-tetrabromo-4,6-dichlorotetradecafluorononane, 1,2 dibromo 4,6,8,10,12,12- hexachlorooctadecafluorododecane, etc.

Other preferred perbromofluorohalogenated oils which are used as base fluids in the present invention include those prepared by brominating other perhalogenated olefinic products of US. Patent 2,742,510; for example, 1,1,4,4-tetrachlorotetrafluorobutene-2,

from 2,3 bis (trifluoromethyl) 2,3 dichlorohexafluorobutane CF -CCl(CF )--CCl(CF )--CF perbromofluorohalogenated oils prepared by the bromination of perfluoroolefins obtained from the decarboxylation of perfluoro monoand dicarboxylic acids wherein n is an integer between 2 and 10 and m is an integer between 0 and 8; and perbromofluorohalogenated oils prepared by the bromination of perchlorofluoroolefins, namely obtained in a minor amount from the decarboxylation, in the case of the monoolefin and the decarboxylation followed by dechlorination in the case of the diolefin of a perchlorofluoromonocarboxylic acid of the formula wherein m in this acid and its derivatives is an integer between 0 and 3. Still other perbromofluorohalogenated oils are obtained by bromochlorinating the double bonds of any of the above-mentioned olefins with at least a stoichiometric amount of bromine chloride at a temperature of between about 20 C. and about C. This addition predominantly takes place with the chlorine atom adding to the terminal carbon atom.

Specific examples of some of these preferred perbromofiuorohalogenated oils are 1,Z-dibromooctafiuorobutane, 1,2,3,4-tetrabromohexafluorobutane, 1,Z-dibromodecafluoropentane, 1,2-dibromododecafluorohexane,

1 ,2-dibromotetradecafluoroheptane, 1,2-dibromohexadecafluorooctane, 1,2-dibromooctadecafluorononane, 1,2-dibromoperfluorodecane, 1,2-dibromopcrfluorohendecane, 1,2-dibromoperfluorododecane, 1,2,4,S-tetrabromooctafluoropentane, 1,2,5 ,6-tetrabromodecafluorohexane, 1,2,6,7-tetrabromododecafluoroheptane, 1,2,7,8-tetrabromotetradecafluorooctane,

l,2,8,9-tetrabromohexadecafiuoronane, 1,2,9,10-tetrabromooctadecafluorodecane, 1,2,10,1 1-tetrabromoperfluorohendecane, 1,2,1 1,1Z-tetrabromoperfluorododecane, 2 bromo-1,4,6,7-tetrachloroundecafluoroheptane, 2-bromo-1,4,5-trichlorooctafluoropentane, 2-bromo-1,4,6,8,9-pentachlorotetradecafluorononane, 2-bromo 1 ,4,6,8, 10, 1 1-hexachloroheptadecafluorohendecane, 2-bromo-1,2,4,5-tetrachloroheptafluoropentane, 2bromo-1,2,4,6,7-pentachlorodecafluoroheptane, 2-bromo-1,2,4,6,8,9-hexachlorotridecafluorononane, 2-bromo-1,2,4,6,8,10,1 1-heptachlorohexadecafluorohendecane, 2,4-dibromo-1,5-dichlorooctafluoropentane, 2,6-dibromol ,4,7-trichloroundecafluoropheptane, 2,8-dibromo-1,4,6,9-tetrachlorotetradecatluorononane, 2,l0-dibromo-1,4,6,8,1 1-pentachloroheptadecafluoro hendecane, 1,2-dibromo-2,4,5 -trichloroheptafluoropentane, 1,2-dibromo-2,4,6,7-tetrachlorodecafluoroheptane, 1,2-dibromo-2,4,6,8,9 pentachlorotridecafluorononane, 1,2-dibromo-2,4,6,8,10,11-hexachlorohexadecafluorohendecane, 1,2,4,5 -tetrabromo-2-chloroheptafluoropentane, 1,2,6,7-tetrabromo-2,4-dichlorodecafluoroheptane, 1,2, 8,9-tetrabromo-2,4,6-trichlorotridecafluorononane, 1,2, 10,1 1-tetrabromo-2,4,6,8-tetrachlorohexadecafiuorohendecane, 2,4-dibromo-1,2,5-trichloroheptafluoropentane, 2,6-dibromo-1,2,4,7-tetrachlorodecafluoroheptane, 2,8-dibromo-1,2,4,6,9-pentachlorotridecafluorononane, 2,10-dibromo-1,2,4,6,8,11-hexachlorohexadecafluorohendecane, 2-bromo-1,4,4-trichlorohexafluorobutane, 2-bromo-1,4,6,6-tetrachlorononafiuorohexane,

2-bromo-1,4,6,8,8-pentachlorododecafluorooctane,

2-bromo-1,4,6,8,10,10-hexachloropentadecafluorodecane,

2-br0m0-1,4,6,8,10,12,12-heptachlorooctadecafluorododecane,

2-bromo-1 -chlorooctafluorobutane,

2-bromo-1-chlorodecafluoropentane,

2-bromo-1-chlorododecafluorohexane,

2-brornol-chlorotetradecafluoroheptane,

2-brorno- 1-ch-lorohexadecafluorooctane,

2-bromo-1-chlorooctadecafluorodecane,

2,3-dibromo-1,4-dichlorohexafluorobutane,

2,4-dibromo-1,5-dichlorooctafluoropentane,

2,5 -dibromo- 1 ,6-dichlorodecafluorohexane,

2,6-dibromo-1,7-dichlorododecafluoroheptane,

2,7-dibromo-1,8-dichlorotetradecafluorooctane,

2,8-dibromo-1,9-dichlorohexadecafluorononane and 2,9-dibromo-1,10-dichlorooctadecafluorodecane.

Other aliphatic hydrofluorohalogenated oils which are suitably employed in the process of this invention are aliphatic alkane oils which aremore than half halogenated. This group includes the bromofiuorohalogenated oils prepared by the hydrobromination of any of the preceding olefins with hydrogen bromide at temperatures between about 50 C. and about 300 C. In the addition reaction, the bromine atoms usually adds to a terminal carbon atom and produces a fi-hydro compound.

Specific examples of some of these bromofluorohalogenated oils are Z-hydro-1-brornotetradecafluoroheptane, -2,6-dihydro-l,7-dibromo-4-chlorododecafluoroheptane,

2-hydro-1-bromo-4,6,8,9-tetrachlorotetradecafluorono nane,

2,9-dihydro-1,10-dibromo-4,6,8-trichloropentadecafluoro decane, 2-hydro-1-bromo-4,6,8,8-tetrachlorodecafluorooctane, 2,10dihydro-1,11-dibromo-4,6,8-trichloroheptadecafluorohendecane, 2-hydro-l-bromooctafluorobutane,

3 2hydro-l-bromodecafluoropentane, 2-hydro-l-bromododecafluorohexane,

'Z-hydro-l-bromotetradecafiuoroheptane,

2-hydro-l-bromohexadecafluorooctane, Z-hydro-1-brornooctadecafluorodecane, 2,3-dihydro-1,4-dibromohexafluorobutane, 2,4-dihydro-1,5-dibromo-octafluoropentane, 2,5 -dihydro 1 ,6-dibromodecafluorohexane, 2,6-dihydro-1,7-dibromododecafluoroheptane, 2,7-di-hydro-1,8-dibromo-tetradecafluorooctane, 2,8-dihydro-1,9-dibromohexadecafluorononane, 2,9-dihydro-1,10-dibromooctadecafluorodecane, 2-hydro-1-bromo-2,4,5-trichloroheptafluoropentane, Z-hydro-1-bromo-2,4,6,7-tetrachlorodecafluoroheptane, 2-hydro-l-bromo-2,4,6,8,9-pentachlorotridecafluorononane, 2-hydro1-bromo-2,4,6,8,10,1l-hexachlorohexadecafluorohendecane, 2,4-dihydro-1,5-dibromo-2-chloroheptafluoropentane, 2,6-dihydro-1,7-dibromo-2,4-dichlorodecafluoroheptane, 2,8-dihydro-1,9-dibromo-2,4,6-trichlorotridecafluorono nane, and 2,l0-dihydro-1,1 l-dibromo-2,4,6,8-tetrachlorohexadecafluorohendecane.

The normally solid polymers of the present invention are those which are compatible with the bromofluorohalogenated oils and which have a DSV between about 0.2 and about 3. The preferred normally solid polymer, or viscosity improver, which is admixed with the broomfluorohalogenated oil is the copolymer of chlorotrifluoroethylene and vinylidene fluoride which has a specific gravity at F. of between about 2.0 and about 2.2, a DSV between about 0.5 and about 2.0 at 266 F. and which contains between about 10 mol percent and about 50 mol percent vinylidene fluoride, most preferably between about 15 mol percent andabout 35 mol percent vinylidene fluoride. The thermoplastic resin containing between about 15 mol percent and about 35 mol percent vinylidene fluoride is commercially available as Kel-F 800 Resin and its method of preparation is described in US. Patent 2,752,332.

Other viscosity improvers which are suitably admixed with the bromofluoroha'logenated oil and which have a DSV at 266 -F. of between about 0.2 and about 3 are solid polymers which have a minimum density of about 0.9 at 100 F. Examples of some of these solid polymers are the silicone rubber gums, polymethacry-late, polyvinyl chloride, polystyrene, polydichlorostyrene, polybutene, vinyl chloride and vinylacetate copolymer, vinyl chloride and acrylonitrile copolymer and chlorinated rubbers.

For good results and ease of mixing, the normally solid polymer should be as finely divided as possible or practical. For example, in the case of Kel-F 800 Resin, a parhole size which will pass percent through a or higher mesh screen (US. Bureau Standards, Standard Screen Series) is preferred.

' required for its use as a gyro fluid. Generally, the addition of normally solid polymer flattens the slope of the ASTM D 341-143 curve, depicting viscosity versus tem perature, so that the fluid solution retains a certain viscosity over a wide temperature range. This is particularly important in meeting the viscosity and pour point specifications for gyro fluids. The flattening of the curve is illustrated in the accompanying drawing which com- 75 pares the slope of a perbromofluorohalogenated oil with l *7 homogeneous mixtures of the oil and a normally solid polymer.

While we do not wish to be bound by any theory of mechanism, it is believed that the shape of the polymer reactor, a thermostatically controlled container with a reflux condenser. When using one of the more volatile major components, such as, for example a perbromofluorochlorinated butane, a reflux condenser is generally molecule changes with a change in temperature so that employed so that light ends escaping from the solution at a high temperature, for example at about 200 F. are returned to the system. or higher, the polymer is extended or uncoiled and exerts In certain cases, where a high density bromofluoroits optimum thickening effect on the bromofluorohalohalogenated oil, for example, 1,2,'3,4-tetrabrornohexagenated oil. At lower temperatures, for example 100 fluorobutane having a density of 2. 63 at 20 C. is mixed F. or lower, the polymer is convoluted or coiled and 10 with a normally solid polymer having high density, the has a more limited effect on the viscosity of the bromospecifications for a particular gyro fluid may require a fiuorohalogenated oil. lower density. In these instances, a cosolvent such as In carrying out the process of the present invention a hydrocarbon ester or silicone containing between about under preferred conditions, the normally solid polymer 5 and about 50 carbon atoms can be added to the bromois added to the bromofluorohalogenated oil at a temperafiuorohalogenated oil to lower the density before mixing ture between about 100 C. and about 125 C., although with the solid polymer or the cosolvent can be added to a temperature between about C. and about 250 C. is the homogeneous solution after mixing has been accomsatisfactory and may be used if desired. The mixture plished. Examples of such cosolvent additives are diis agitated vigorously for a period of from about 1 to octylphthalate, dioctylazelate, didecylazelate, dihexylsebabout 100 hours or until a homogeneous solution and a 20 acate, dibutylglutarate, dioctylsuccinate, silicone oils, etc. constant viscosity is obtained. To insure the complete These additives are added in an amount between about homogeneity, the resulting solution can be filtered to 0.5 weight percent and about 50 weight percent, preferremove any gel-like particles which may be formed in ably 2 weight percent and about 20 weight percent based the solution. The filtration step is usually omitted when on the oil. the solution has achieved complete homogeneity upon In other cases the homogeneous solution obtained from being mixed for a suflicient period of time. the mixing of the bromofluorohalogenated oil and the Although it is preferable and less time consuming in normally solid polymer is used directly as a high viscosthe mixing of ingredients to add the normally solid polyity fluid in gyro mechanisms and is generally introduced mer to the bromofluorohalogenated oil, it is also within into the gyroscope cavity under vacuum. the scope of the present invention to add the oil to the The following examples are offered as a better undersolid polymer. This is accomplished by mixing a small standing of the present invention and are not to be conamount of oil with the solid polymer so as to moisten strued as unnecessarily limiting thereto. the particles and then adding the remaining portion of oil The following homogeneous solutions of Examples 1, to the moistened solid polymer. Generally, to carry 2, 3, 4, 6 and 7 reported in Table II were prepared by out this procedure, a longer period of time with agitation adding the pulverized normally solid polymer to the peris required in order to arrive at a substantially homogebromochloroiluorinated oil in a glass flask equipped with neous solution, for example, a period between about 10 a thermometer, a Hershberg stirrer and a condenser. to about 200 hours. The mixture was heated to a temperature of 100 C. If several concentrations of normally solid polymer are and was agitated during and after the addition of the to be P p in the Same Pefbfomoflllofohalogenated solid polymer for a period of about 48 hours, whereupon oil, it is often convenient to prepare a stock solution of a homogeneous solution having a constant viscosity was higher normally solid polymer concentration than is rebtain d, quired and then dilute the stock solution with oil until Th e aratio of the solution of Example 5 required the required concentration is attained. no heating since polybutene is soluble in the oil at room The reaction may be carried out in any suitable retemperature. This mixture was stirred for a period of actor such as, for example, an open glass flask, a metal about one hour before using.

Table II HOMOGENEOUS SOLUTIONS CONTAINING 1,2-DIBROM0-4,4-DIOHLOROHEXAFLUOROBUTANE, 13.1. 169 0.

Weight Viscosity DSV 01' Percent ASTM Density Example No. Solid Polymer Solid of Solid Slope Pour Point, F. at 20 C Polymer Polymer cs., 05., 01).,

210 F F. 100 F Kel-F s00 Resin 2. 0 135 092 1, 488 0.3 less than 80.--. 2.184 do 1.0 11.12 37.75 81 0.43 do 2.190 on 7.5 44.5 317 682 0.450 2.177 moo 10. 0 1, 04a 2, 240 0. 4a 2. 167 Polybutene (Molecular Weight 750)...- 15. 0 1. 71 5. 8. 8 0. 77 1. 788 Silicone rubber gum (SE-76) from 6.0 149 361.4 726 0.18 2. 040

General Electric. do 7.5 319 753.7 1, 480 0.15 do 2.002 CFgBt-OFBr-OFa-CFCI:010118..-- 0. 52 1. 2.3 1.06 less than -s5- 2.1957

1,2,8,9-TETRABROM0-4.0-DIOHLOROTETRADEOAFLUORONONANE SOLUTION 1 Other silicone rubber gums which are supplied by General Electric and which may be used in place of SE76 include Silicone SE-52, Silicone SE-30, Silicone SE51, Silicone SE33 and Silicone SE-3l. All of the homogeneous solutions prepared in the above examples, numbers 1 through 7 have clear points below room temperature (20 0.).

Silicone rubber gum SE-76 is a clear, colorless silicone polymer with a specific gravity of 0.98, a petetration (ASTMD217) of 100-200 mm/minute using a 54 inch diameter cylindrical foot and a 100 gram shaft load, and a Williams plasticity (ASSM D926, room temperature, 3 minutes) of 0.035 to 0.045 inch.

The properties of some perbromofluorohalogenated oils which may be used in place of 1,2-dibromo-4,4-dichlorohexafluorobutane to produce desirable homogeneous solutions for use in gyros are given below in Tacent vinylidene fluoride, and an alkane oil comprising an aliphatic perbromofluorohalogenated oil which contains between 4 and 12 carbon atoms per molecule, the bromine substituted carbon atoms thereof being further ble substituted only by normally gaseous halogen atoms.

Table III PERBROMOFLUOROHALO GENATED OILS Bolling Pour Viscosity, cs. N 0. Compound Point, Point, M 1m O./rnm 0.

1 1,2,3,4-tetrabromohexafluorobutane, 95/20 60 2.627 1.468 1.78 0.74

CF1BrOFBrOFBrOF1Br. 2 1,2-clibrorno-4,6,6-trichlorononafluorohexane, 124/25 65 2.172 1. 425 2.70 0.93

OF2B1CFBI(CF2-OFO1)2CL 3 1,2,8.9-tetrabromo-4,6-diehlorotetradecafiuorononane, 111-2]. 08 -25 2. 395 1. 440 28. 6 3. 21

CF2BlCFBI(CFrCFOD CFQGFBIOFRBI.

It is to be understood, without departing from the scope of this invention, that, in addition to the few perbromofluorohalogenated oils listed in Table HI, any of the other aliphatic bromofluorohalogenated oils containing between 4 and 12 carbon atoms per molecule, particularly the perbromofluorinated and perbromofluorochlorinated oils, can be used with any of the normally solid polymers having a DSV of between about 0.2 and about 3, to produce highly viscous, thermally stable, homogeneous solutions suitable for use as damping and flotation fluids. The preparation of these viscous materials can be effected by any of the methods set forth herein and many modifications and embodiments of these methods may become apparent to those skilled in the art from the above disclosure.

The highly viscouse materials of this invention are stable in contact with metals such as, for example, aluminum, magnesium, coin silver and brass and do not react with most chemical reagents or other resinous materials at temperatures up to 100 F. or higher. These materials having high densities and pour points well below room temperature retain their viscosity over a wide temperature range up to temperatures of about 200 F. or higher. The properties of these materials make them useful in many of the applications for which highly viscous thermally stable materials are demanded, for example, as gyro fluids, as chemical seal pulsation dampeners, as lubricants, as hydraulic fluids and as viscosity index improvers.

Having thus described our invention we claim:

1. A highly viscous, thermally stable homogeneous solution having a high density and low pour point which consists essentially of between about 0.2 and about 30 weight percent of a normally solid, soluble copolymer of chlorotrifluoroethylene and vinylidene fluoride having a dilute solution viscosity between about 0.2 and about 3.0 and containing between about 10 and about 50 mol percent vinylidene fluoride, and an alkane oil comprising an aliphatic bromofluorohalogenated oil which is at least half halogenated and which contains between 4 and 12 carbon atoms per molecule, the bromine substituted carbon atoms thereof being further substituted only by normally gaseous halogen atoms.

2. The solution of claim 1 wherein the bromofluorohalogenated oil is a ii-hydroperbromofluorinated oil.

3. The solution of claim 1 wherein the bromofluoro halogenated oil is a fi-hydroperbromofluorochlorinated oil.

4. A highly viscous, thermally stable homogeneous solution having a high density and low pour point which consists essentially of between about 0.2 and about 30 weight percent of a normally solid, soluble copolymer of chlorotrifluoroethylene and vinylidene fluoride having a dilute solution viscosity between about 0.2 and about 3.0 and containing between about 10 and about 50 mol per- 5. The solution of claim 4 wherein the perbromofluorohalogenated oil is a perbromofluorinated oil.

6. The solution of claim 4 wherein the perbromofluorinated oil is 1,2,3,4-tetrabromohexafiuorobutane.

7. The solution of claim 4 wherein the perbromofluorohalogenated oil is a perbromofluorochlorinated oil.

8. The solution of claim 4 wherein the perbromofluorochlorinated oil is 1,2-dibromo-4,4-dichlorohexafluorobutane.

9. The solution of claim 4 wherein the perbromofluorochlorinated oil is 1,2,8,9-tetrabromo-4,6-dichlorotetradecafluorononane.

10. The solution of claim 4 wherein the perbromofluorochlorinated oil is a mixture of oils obtained from the brornination of a mixture of chlorotrifluoroethylene polymer pyrolysis products.

11. In the method of operating a gyro mechanism containing a gyro operating in a fluid medium the improvement which consists of using as the fluid medium a homogeneous gyro fluid consisting essentially of between about 0.2 and about 30 weight percent of a normally solid, soluble copolymer of chlorotrifluoroethylene and vinylidene fluoride having a dilute solution viscosity between about 0.2 and about 3.0 and containing between about 15 and about 35 mol percent vinylidene fluoride, and an alkane oil comprising an aliphatic bromofluorohalogenated oil which is more than half halogenated and which contains between 4 and 12 carbon atoms per molecule, the bromine substituted carbon atoms thereof being further substituted only by normally gaseous halogen atoms.

References Cited in the file of this patent UNITED STATES PATENTS 2,524,590 Boe Oct. 3, 1950 2,583,588 Calvin Jan. 29, 1952 2,584,222 OConnor Feb. 5, 1952 2,628,196 Coonradt et al Feb. 10, 1953 2,636,861 Watson Apr. 28, 1953 2,676,193 Ruh Apr. 20, 1954 2,681,940 Ruh June 22, 1954 2,742,510 Davis Apr. 17, 1956 2,748,098 Passino May 29, 1956 2,766,157 Peterson Oct. 9, 1956 2,770,615 Kroncke Nov. 13, 1956 2,837,550 Prober June 3, 1958 2,842,603 Miller July 8, 1958 2,875,253 Barnhart Feb. 24, 1959 FOREIGN PATENTS 734,644 Great Britain Aug. 3, 1955 OTHER REFERENCES Kalichevsky-Kobe: Petroleum Refining with Chemicals, 1956, Elsevier Publ. 00., pages 548-552. 

1. A HIGHLY VISCOUS, THERMALLY STABLE HOMOGENEOUS SOLUTION HAVING A HIGH DENSITY AND LOW POUR POINT WHICH CONSISTS ESSENTIALLY OF BETWEEN ABOUT 0.2 AND ABOUT 30 WEIGHT PERCENT OF A NORMALLY SOLID, SOLUBLE COPOLYMER OF CHLOROTRIFLUOROETHYLENE AND VINYLIDENE FLUORIDE HAVING A DILUTE SOLUTION VISCOSITY BETWEEN ABOUT 0.2 AND ABOUT 3.0 AND CONTAINING BETWEEN ABOUT 10 AND ABOUT 50 MOL PERCENT VINYLIDENE FLUORIDE, AND AN ALKANE OIL COMPRISING AN ALIPHATIC BROMOFLUOROHALOGENATED OIL WHICH IS AT LEAST HALF HALOGENATED AND WHICH CONTAINS BETWEEN 4 AND 12 CARBON ATOMS PER MOLECULE, THE BROMINE SUBSTITUTED CARBON ATOMS THEREOF BEING FURTHER SUBSTITUTED ONLY BY NORMALLY GASEOUS HALOGEN ATOMS. 